GB1454491A - - Google Patents

Abstract

1454491 Inspecting for leaks and defects FOSTER WHEELER Ltd 4 March 1966 [16 Dec 1964] 51212/64 Heading G1S [Also in Division F2] A testing and/or repairing tool for use within the headers of heat exchangers, the heat exchange surface of which comprises tubes that have their ends fixed in tube holes in the longitudinal walls of one or more elongated headers extending perpendicularly to the tubes, comprises a working tool head carrying a testing and/or repairing device and being pivotally mounted on a boom so as to be capable of being swung in line with the boom during its insertion through an access hold in the end of a header by control means operable from outside the header, manipulating means extending along the boom for bringing the testing and/or repairing device into working relationship with a tube hole in the header longitudinal wall and which are also operable from outside the header. Such a tool has the advantage of only requiring relatively small holes in the header and also the surrounding shell, when present, with the result that the header and the shell do not have to be made much stronger in the regions of these holes. In the case of heat exchangers used in nuclear installations, the tool operator can be positioned away from the header and be shielded at least to some extent from any radio-activity. The tool may include an introscope arranged to view in the region of the tool head so that the operator can look for leaks and watch the operation of the tool head. The tool head is movable both along and around the header so that it can be brought to work on the end of any of the tubes connected to the header. It is also movable radially of the boom towards and away from the end of a tube. It may have mounted on it a number of devices to effect different operations on a tube. Thus, initially a locating plug may be fitted to the head for setting up the tool for a particular leaking tube. Next a reaming tool may be fitted to form a good seating for a plug. Finally a pneumatic hammer may be fitted to drive a plug into the tube by repeated blows. The boom member has a support at one end which is fixed to the outside of the header or shell and a locating boss at the other end which is inserted into a corresponding hole in the end of the header opposite that through which the tool is inserted. Defective tubes can be located by pressurizing a liquid such as water within the shell and watching for drops to appear at the holes in the header. Alternatively, the shell can be pressurized with argon or other gas or vapour and the working head fitted with a suitable detector probe. Weld defects can be located by means of an ultrasonic probe.